Design and Practice of Undergraduate Biochemistry Experiments Based on the DOK Model: A Case Study of HPLC Quantification of TMZ in Mouse Tissues.

While biochemistry laboratory instruction continuously evolves to enhance student learning, effectively cultivating higher-order thinking skills in complex experimental settings remains an ongoing challenge. By applying the Depth of Knowledge (DOK) model, we designed and implemented a comprehensive experiment titled "Determination of Temozolomide Content in Mouse Tissues Using High-Performance Liquid Chromatography (HPLC)" for undergraduate bioscience majors. This experiment helps students understand drug tissue distribution mechanisms while filling a curricular gap in teaching pharmacokinetic analysis in complex biological samples. Based on the DOK framework, we designed a four-level task chain-Recall, Skill, Strategy, and Innovation-shifting the pedagogical focus from basic technical training to the systematic cultivation of higher-order thinking skills. Educational evaluation revealed high student satisfaction and demonstrated that the DOK-based approach significantly improved students' higher-order cognitive abilities, particularly in strategic analysis and innovation, compared to traditional instruction. Consequently, this study provides an effective practical case and a transferable paradigm for systematically fostering higher-order thinking in science laboratory education.